The manhunt for ex-cop Christopher Dorner played out in real time on television. On Twitter and other social media, many expressed support for the suspect's alleged killing spree and his claims against LAPD.

The manhunt for former LAPD officer Christopher Dorner reached its climax Tuesday night with dramatic shootouts and leaping flames engulfing a mountain hideout. Authorities believe the cabin, sequestered in a gully near the resort town of Big Bear Lake, about 90 miles east of Los Angeles, is where the suspect ended his flight. Charred human remains, yet to be identified, were found in the burned cabin late Tuesday night.

The daylong rampage, involving two hostages and a carjacking, also claimed the life of a fourth victim, a sheriff’s deputy. The San Bernardino officer was shot as the suspect tried a desperate escape from the cabin during the afternoon.

Startlingly raw footage of ferocious gunfights played all day on local television stations as newscasters awaited more information about the search. At the same time, a drumbeat of social media support grew louder for the man dismissed by the Los Angeles Police Department four years ago for allegedly lying to investigators about an incident of police brutality. Mr. Dorner had claimed that a fellow officer had kicked a suspect.

All this is part of what many observers call yet another instance of a rapidly escalating tide of extreme violence, laced with increased resentment of police in certain communities.

“We have a culture of more and more extreme behavior," says Najee Ali, a well-known black activist and executive director of Project Islamic H.O.P.E. in Los Angeles, which he says shows up in everything from video games to TV and movies. At the same time, he adds, “we are seeing a growing culture of resentment for police brutality that is overlooked and tolerated in communities of color.” When something like this happens, extraordinary as the details are, the fundamental narrative of unfairness at the hands of law enforcement is strong, he says.

This extremism is apparent in many details of the Dorner case from this past week, says Tom Fuentes, former assistant FBI director, as he spoke with CNN during the day.

Dorner’s 10-day rampage began with two murders, one victim the daughter of the man who had defended him in a 2008 disciplinary hearing, after which Dorner was fired. As the killing began, the 33-year-old former Navy reservist posted an online manifesto detailing his belief that he had been wrongly fired. The 5,900-word blast also included a promise to kill not only officers he felt had wronged him, but also members of their families. LAPD officers have been on high-alert guard duty for some 50 family members of its personnel for nearly a week, straining the department's capacity for routine law enforcement.

Mr. Fuentes, who has had years of experience in dealing with the Mafia and South American drug cartels, noted that targeting families as a means of terrorism happens routinely in other nations. But in American communities, this “is new," he said on CNN, "something we have not seen before in this country.”

It is particularly chilling set against the backdrop of mounting police deaths, he added. Even as law enforcement officers outside the Loma Linda Medical Center mourned the loss of the San Bernardino sheriff’s deputy on Tuesday – with a full cortege of police cars proceeding behind the coroner’s wagon carrying the slain officer – social media such as Facebook and Twitter were bristling with support for Dorner's claims of police brutality and mistreatment, including encouragement for him to shoot more police officers. Chatter in local bars overheard by reporters also included support for Dorner’s murderous quest.

This sort of folk-hero status for an alleged murderer sets the teeth of many officials on edge, said Todd Spitzer, Orange County supervisor, in an interview with CNN. He says he overheard such conversations in local shops. “This man is nothing more than a murderer," he added, not someone worthy to stand beside the law enforcement personnel who risk their lives on a daily basis.

Still, neighborhood activists say the anti-police sentiment fired up by Dorner's claims and the week-long manhunt to find him are not going to just fade away.

“That’s why you are seeing it all over Facebook and Twitter,” says Mr. Ali. “We are going to see more violence and more disrespect for law enforcement until something is done to turn this around in a way that people will believe."